JDBC 增删改查

public class NoteDAOImpl implements NoteDAO {  
    // 增加操作  
    public void insert(Note note) throws Exception {  
        String sql = "INSERT INTO note(id,title,author,content) VALUES(note_sequ.nextVal,?,?,?)" ;  
        PreparedStatement pstmt = null ;  
        DataBaseConnection dbc = null ;  
        dbc = new DataBaseConnection() ;  
        try {  
            pstmt = dbc.getConnection().prepareStatement(sql) ;  
            pstmt.setString(1,note.getTitle()) ;  
            pstmt.setString(2,note.getAuthor()) ;  
            pstmt.setString(3,note.getContent()) ;  
            pstmt.executeUpdate() ;  
            pstmt.close() ;  
        } catch (Exception e) {  
            // System.out.println(e) ;  
            throw new Exception("操作中出现错误！！！") ;  
        } finally {  
            dbc.close() ;  
        }  
    }  
    // 修改操作  
    public void update(Note note) throws Exception {  
        String sql = "UPDATE note SET title=?,author=?,content=? WHERE id=?" ;  
        PreparedStatement pstmt = null ;  
        DataBaseConnection dbc = null ;  
        dbc = new DataBaseConnection() ;  
        try {  
            pstmt = dbc.getConnection().prepareStatement(sql) ;  
            pstmt.setString(1,note.getTitle()) ;  
            pstmt.setString(2,note.getAuthor()) ;  
            pstmt.setString(3,note.getContent()) ;  
            pstmt.setInt(4,note.getId()) ;  
            pstmt.executeUpdate() ;  
            pstmt.close() ;  
        } catch (Exception e) {  
            throw new Exception("操作中出现错误！！！") ;  
        } finally {  
            dbc.close() ;  
        }  
    }  
    // 删除操作  
    public void delete(int id) throws Exception {  
        String sql = "DELETE FROM note WHERE id=?" ;  
        PreparedStatement pstmt = null ;  
        DataBaseConnection dbc = null ;  
        dbc = new DataBaseConnection() ;  
        try {  
            pstmt = dbc.getConnection().prepareStatement(sql) ;  
            pstmt.setInt(1,id) ;  
            pstmt.executeUpdate() ;  
            pstmt.close() ;  
        } catch (Exception e) {  
            throw new Exception("操作中出现错误！！！") ;  
        } finally {  
            dbc.close() ;  
        }  
    }  
    // 按ID查询，主要为更新使用  
    public Note queryById(int id) throws Exception {  
        Note note = null ;  
        String sql = "SELECT id,title,author,content FROM note WHERE id=?" ;  
        PreparedStatement pstmt = null ;  
        DataBaseConnection dbc = null ;  
        dbc = new DataBaseConnection() ;  
        try {  
            pstmt = dbc.getConnection().prepareStatement(sql) ;  
            pstmt.setInt(1,id) ;  
            ResultSet rs = pstmt.executeQuery() ;  
            if(rs.next()) {  
                note = new Note() ;  
                note.setId(rs.getInt(1)) ;  
                note.setTitle(rs.getString(2)) ;  
                note.setAuthor(rs.getString(3)) ;  
                note.setContent(rs.getString(4)) ;  
            }  
            rs.close() ;  
            pstmt.close() ;  
        } catch (Exception e) {  
            throw new Exception("操作中出现错误！！！") ;  
        } finally {  
            dbc.close() ;  
        }  
        return note ;  
    }  
    // 查询全部  
    public List queryAll() throws Exception {  
        List all = new ArrayList() ;  
        String sql = "SELECT id,title,author,content FROM note" ;  
        PreparedStatement pstmt = null ;  
        DataBaseConnection dbc = null ;  
        dbc = new DataBaseConnection() ;  
        try {  
            pstmt = dbc.getConnection().prepareStatement(sql) ;  
            ResultSet rs = pstmt.executeQuery() ;  
            while(rs.next()) {  
                Note note = new Note() ;  
                note.setId(rs.getInt(1)) ;  
                note.setTitle(rs.getString(2)) ;  
                note.setAuthor(rs.getString(3)) ;  
                note.setContent(rs.getString(4)) ;  
                all.add(note) ;  
            }  
            rs.close() ;  
            pstmt.close() ;  
        } catch (Exception e) {  
            System.out.println(e) ;  
            throw new Exception("操作中出现错误！！！") ;  
        } finally {  
            dbc.close() ;  
        }  
        return all ;  
    }  
    // 模糊查询  
    public List queryByLike(String cond) throws Exception {  
        List all = new ArrayList() ;  
        String sql = "SELECT id,title,author,content FROM note WHERE title LIKE ? or AUTHOR LIKE ? or CONTENT LIKE ?" ;  
        PreparedStatement pstmt = null ;  
        DataBaseConnection dbc = null ;  
        dbc = new DataBaseConnection() ;  
        try {  
            pstmt = dbc.getConnection().prepareStatement(sql) ;  
            pstmt.setString(1,"%"+cond+"%") ;  
            pstmt.setString(2,"%"+cond+"%") ;  
            pstmt.setString(3,"%"+cond+"%") ;  
            ResultSet rs = pstmt.executeQuery() ;  
            while(rs.next()) {  
                Note note = new Note() ;  
                note.setId(rs.getInt(1)) ;  
                note.setTitle(rs.getString(2)) ;  
                note.setAuthor(rs.getString(3)) ;  
                note.setContent(rs.getString(4)) ;  
                all.add(note) ;  
            }  
            rs.close() ;  
            pstmt.close() ;  
        } catch (Exception e) {  
            System.out.println(e) ;  
            throw new Exception("操作中出现错误！！！") ;  
        } finally {  
            dbc.close() ;  
        }  
        return all ;  
    }  
};